In order to play any of the classes effectively you gotta keep your eyes glued to your character frame buffs. Is there any easier way to do this?

It wouldn't be as bad if the procs and such were always in the same place, but when you leave or join a group everything changes position. I spend most of my time just hunting down which icon has come up.

Is there a way to change the size of specific buffs and/or debuffs? Or locations? Or graphics? Possibly a whitelist/blacklist to show only my debuffs on the target or perhaps only the buffs I care about on my own character?

It's going to sound lame but rotations are the key. There are sound effects that go with each of your class's abilities. When you hear one sound use the next ability. Buy a target dummy, close your eyes(knowing your hotkeys) and feel it out. Keep them open at first to learn the associations then jump into it. It becomes second nature eventually.

Granted some classes have specific rotations that can guarantee outcomes. Need a crit to proc before you get a free next ability...use your ability that causes the first to crit 100% of the time.

Snipers/gunslingers come to mind. When your snipe/series of shots crits // charged burst/speed shot crits you get a faster ambush/aimed shot(huge dmg+armor pen ability). So you use your lase target/smugglers luck to make it crit 100% then use the perk. Granted this ability isn't always ideal for your energy but it helps a lot. If you use guaranteed crits for abilities that enable other abilities then you don't need to watch your buffs all the time.

My next suggestion is even worse...play a healing class. I know I know, it'd bad, but you will learn every buff and debuff in the game. Some you can cleanse because they are force or physical or tech abilities. Others you may not be able to cleanse but you will learn quick enough.

The learning curve is natural within flashpoints for this. You may struggle as a sage/inquisitor in athiss from the main boss debuff ,for example, but then you get the cleanse for it and it's almost too easy to finish. When the expansion procs you will still have to learn them but they can be larger which will make them easier to spot.

The last hurdle is that your mirror imp/pub class has a different icon for the debuff than you will be used to. Even if it's bigger then you have to learn it and roll with it.

Tldr: Read buffs/debuffs to learn them. Learn abilities that cause instant buffs/debuffs and learn your mirror classes abilities for the best outcome. Bigger does not mean less work with regards to learning.